Roller cone drill bits are used to form wellbores in subterranean formations. Such drill bits generally include at least one support arm and often three support arms. A respective cone assembly may be rotatably mounted on interior portions of each support arm.
Each cone assembly often includes a base with a cavity or opening formed therein. Each cone cavity may be sized to receive exterior portions of an associated journal or spindle to allow rotation of the cone assembly relative to the associated journal or spindle while drilling a wellbore. A wide variety of bearings, bearing assemblies, bearing surfaces, seals and/or other supporting structures may be disposed between interior portions of each cone assembly and exterior portions of the associated journal or spindle.
Roller cone drill bits often include lubricant systems to supply lubricant to journals, bearings, bearing assemblies, bearing surfaces, seals and/or other supporting structures associated with rotation of each cone assembly mounted on a respective support arm. A variety of lubricants may be used with roller cone drill bits to accommodate rotation of each cone assembly relative to the respective spindle. A wide variety of seals and seal assemblies may be used to block communication between downhole well fluids and lubricants associated with rotation of each cone assembly. Various types of systems have been used to maintain lubricant system pressure to minimize potential damage to bearings, bearing assemblies, seals, journals and other supporting structures associated with rotation of a cone assembly relative to an associated support arm.
When a lubricant system includes an intergland system and a separate bearing lubrication system, although bearing greases commonly contain a number of additives, the intergland grease is typically additive-free.